771640861 has 2 divisors, whose sum is σ = 771640862. Its totient is φ = 771640860.

The previous prime is 771640853. The next prime is 771640889. The reversal of 771640861 is 168046177.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 734735236 + 36905625 = 27106^2 + 6075^2 .

It is a cyclic number.

It is not a de Polignac number, because 771640861 - 2³ = 771640853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (771640811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 385820430 + 385820431.

It is an arithmetic number, because the mean of its divisors is an integer number (385820431).

Almost surely, 2^771640861 is an apocalyptic number.

It is an amenable number.

771640861 is a deficient number, since it is larger than the sum of its proper divisors (1).

771640861 is an equidigital number, since it uses as much as digits as its factorization.

771640861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56448, while the sum is 40.

The square root of 771640861 is about 27778.4243793632. The cubic root of 771640861 is about 917.2162470692.

The spelling of 771640861 in words is "seven hundred seventy-one million, six hundred forty thousand, eight hundred sixty-one".